1. Field of Invention
Embodiments generally relate to remote (non-physical contact) detection and identification of materials, including for example, concealed contraband materials such as explosives, explosives precursors, and narcotics.
2. Related Art
Detection of concealed materials remains very important for military operations, border security, and travel security, especially by air. Although many detection and identification arrangements and methods have been deployed, proposed and attempted, existing detection capabilities remain inadequate.
Detection methods in use at the time of filing this patent document employ various technologies and techniques, including magnetic field sensors, x-ray detectors, radars, terahertz (THz) imaging, odor sensors, and ultrasonic arrays. While detection of even small quantities of metal is relatively easy to do with current technology, such as, for example, magnetic field sensors, detection and discrimination of non-conducting materials is more difficult.
The presence of certain substances can be detected using odor sensors, also known as electronic noses or sniffers. Small numbers of molecules in the air can be detected. However, this approach is inadequate to detect concealed substances. Materials can be either tightly packed, not have sufficient volatility, or be omnipresent in a region where measurements must be made. For example, in a war zone, traces of explosives are commonly present in the air, so detection of explosives is “masked” by ambient levels.
X-ray measurement systems are excellent at providing images of shapes of materials, but have limited capability to distinguish one material from another based on X-ray absorption and/or transmission properties. Many materials of vastly different composition have identical X-ray absorption and/or transmission properties. For example, x-ray images of a book and a rectangular piece of plastic explosive can appear very similar.
In order to better detect and discriminate among materials, what is needed is the ability to determine both a concealed object's shape and provide information about its chemical composition.
Features and advantages of the invention will become more apparent from the detailed description of various embodiments of the invention set forth below when taken in conjunction with the drawings, in which like reference characters refer to corresponding elements throughout. Like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. In most cases, the drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.